arch/x86/kernel/cpu/mshyperv.c

   1 /*
   2  * HyperV  Detection code.
   3  *
   4  * Copyright (C) 2010, Novell, Inc.
   5  * Author : K. Y. Srinivasan <ksrinivasan@novell.com>
   6  *
   7  * This program is free software; you can redistribute it and/or modify
   8  * it under the terms of the GNU General Public License as published by
   9  * the Free Software Foundation; version 2 of the License.
  10  *
  11  */
  12
  13 #include <linux/types.h>
  14 #include <linux/time.h>
  15 #include <linux/clocksource.h>
  16 #include <linux/module.h>
  17 #include <asm/processor.h>
  18 #include <asm/hypervisor.h>
  19 #include <asm/hyperv.h>
  20 #include <asm/mshyperv.h>
  21
  22 struct ms_hyperv_info ms_hyperv;
  23 EXPORT_SYMBOL_GPL(ms_hyperv);
  24
  25 static bool __init ms_hyperv_platform(void)
  26 {
  27         u32 eax;
  28         u32 hyp_signature[3];
  29
  30         if (!boot_cpu_has(X86_FEATURE_HYPERVISOR))
  31                 return false;
  32
  33         cpuid(HYPERV_CPUID_VENDOR_AND_MAX_FUNCTIONS,
  34               &eax, &hyp_signature[0], &hyp_signature[1], &hyp_signature[2]);
  35
  36         return eax >= HYPERV_CPUID_MIN &&
  37                 eax <= HYPERV_CPUID_MAX &&
  38                 !memcmp("Microsoft Hv", hyp_signature, 12);
  39 }
  40
  41 static cycle_t read_hv_clock(struct clocksource *arg)
  42 {
  43         cycle_t current_tick;
  44         /*
  45          * Read the partition counter to get the current tick count. This count
  46          * is set to 0 when the partition is created and is incremented in
  47          * 100 nanosecond units.
  48          */
  49         rdmsrl(HV_X64_MSR_TIME_REF_COUNT, current_tick);
  50         return current_tick;
  51 }
  52
  53 static struct clocksource hyperv_cs = {
  54         .name           = "hyperv_clocksource",
  55         .rating         = 400, /* use this when running on Hyperv*/
  56         .read           = read_hv_clock,
  57         .mask           = CLOCKSOURCE_MASK(64),
  58 };
  59
  60 static void __init ms_hyperv_init_platform(void)
  61 {
  62         /*
  63          * Extract the features and hints
  64          */
  65         ms_hyperv.features = cpuid_eax(HYPERV_CPUID_FEATURES);
  66         ms_hyperv.hints    = cpuid_eax(HYPERV_CPUID_ENLIGHTMENT_INFO);
  67
  68         printk(KERN_INFO "HyperV: features 0x%x, hints 0x%x\n",
  69                ms_hyperv.features, ms_hyperv.hints);
  70
  71         clocksource_register_hz(&hyperv_cs, NSEC_PER_SEC/100);
  72 }
  73
  74 const __refconst struct hypervisor_x86 x86_hyper_ms_hyperv = {
  75         .name                   = "Microsoft HyperV",
  76         .detect                 = ms_hyperv_platform,
  77         .init_platform          = ms_hyperv_init_platform,
  78 };
  79 EXPORT_SYMBOL(x86_hyper_ms_hyperv);